

// leetcode 104. 二叉树的最大深度
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 * int val;
 * TreeNode left;
 * TreeNode right;
 * TreeNode() {}
 * TreeNode(int val) { this.val = val; }
 * TreeNode(int val, TreeNode left, TreeNode right) {
 * this.val = val;
 * this.left = left;
 * this.right = right;
 * }
 * }
 */
//class Solution {
//    public int maxDepth(TreeNode root) {
//        if (root == null) return 0;
//        int leftTree = maxDepth(root.left);
//        int rightTree = maxDepth(root.right);
//        return Math.max(leftTree, rightTree) + 1;
//    }
//}